Created attachment 170372 [details]
Panel with the blue rectangle leaking outside of it

SUMMARY
After login the panel looks as expected. Once it is unfloated (by maximizing a window or moving it towards the panels edge) and floated again, however, it has a solid blue background underneath it extended slightly to the bottom right next to it.

STEPS TO REPRODUCE
1. Have a floating panel
2. Drag a window next to it
3. Drag the window away from the panel

OBSERVED RESULT
The panel now has a blue background extending outside of it to the bottom and right.

EXPECTED RESULT
The panel should not have any background as it was upon a fresh plasma session start.

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 40
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.1
Kernel Version: 6.8.11-300.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7840U w/ Radeon 780M Graphics
Memory: 30.7 GiB of RAM
Graphics Processor: AMD Radeon 780M
Manufacturer: Framework
Product Name: Laptop 13 (AMD Ryzen 7040Series)
System Version: A7